This invention relates to a device for sequentially injecting a large number of small animals, such as chicks, ducklings, young turkeys, and guinea fowl with a desired substance. Such devices are in common use, particularly in the hatchery industry, and representative examples of such devices are disclosed, for instance, in U.S. Pat. Nos. 3,641,998 to Lyon et al. and 3,964,481 to Gourlandt et al.
Devices of this general type typically comprise a work plate on which an animal to be injected can be position, a needle-type syringe (spray-type syringes may also be used in functionally similar devices) mounted on the opposite side of the work plate from the side on which the animal to be injected is positioned during use of the device, first means for moving the syringe back and forth between a first position in which the syringe needle is entirely withdrawn on the opposite side of the work plate and a second position in which the syringe needle protrudes through an aperture in the work plate, and second means for detecting the presence of an animal to be injected in position on the work plate and for activating the first means. In the past, the first means has been an electric motor, but such motors have proved to be not entirely satisfactory for several reasons. In the first place, such motors have caused some safety problems, particularly in the wet environment of hatcheries. In the second place, while such machines may be portable, they can be used only in the vicinity of a source of wall current. And, in the third place, such motors have imposed a limitation on the number of animals which can be injected per unit of time which is less than the rate which a skilled operator is capable of achieving. Accordingly, it has long been known that it would be desirable to find an alternate syringe actuator not suffering from these drawbacks.
It is known in the art that sometimes variations of penetration and/or dosage is required, as in successive treatments or for different sizes and ages of the animals being injected, and various means are employed to permit such variations. However, the means now in use have been found to be unduly complex, not completely accurate, and to be somewhat lacking in reliability, particularly with respect to variations in the extent of penetration.
Despite the best efforts of the user of such devices, the environment in which they are used is typically far from clean, and the devices are often subject to rough usage. Accordingly, it has often been necessary to open up the device to inspect and, if necessary, clear or repair operative components. This operation, of course, takes time and is particularly irritating when, after opening up the machine, it is found that no cleaning or repairing is necessary.
The syringe has to be taken out, cleaned, sterilized, and replaced one or two times daily. Accordingly, it is imperative that the syringe be easily and quickly removed and replaced, and various "quick connect" devices for attaching the syringe to the activating apparatus have been proposed. All, however, have been more or less unsatisfactory due to excessively complicated parts, excessive operation time, and/or a tendency to cause bending of the syringe shafts during use.
The problems suggested in the preceding are not intended to be exhaustive, but rather are among many which tend to reduce the effectiveness of prior injection devices. Other noteworthy problems may also exist; however, those presented above should be sufficient to demonstrate that injection devices appearing in the prior-art have not been altogether satisfactory.